In battlefield communications there is a clear and important need to have individual soldiers in combat in constant, reliable and secure wireless communication with the field command center. Realization of such communication systems requires that an omnidirectional antenna system be conveniently located and accessible to the soldier at all times, particularly when in a rapidly mobile environment. There is also a need for a system capable of receiving the Global Positioning System (GPS) signal whereby the soldier is able to determine his precise location.
Although a pocket sized VHF radio transceiver could satisfy many of the communication requirements, the need for secure communication, and transmission of video data and high data rate communications requires a system which operates with larger bandwidth. Furthermore, for unobstructed communication for all physical positions of the soldier in the battle field it is a virtual necessity that the antenna be so placed on the person of the soldier that the antenna receives continuous coverage from the operating transmitter.
While omnidirectional or wide angle coverage can be provided by monopole rod antennas, helical antennas, and quadrafiller helix or conical helix antennas, such antennas, which are not conformed to the surface of the supporting structure on which the antenna resides, are easily identifiable and are more likely to be damaged or rendered inoperative.
Rapid advances in microwave, integrated circuit technology, communication technology, display technology and several other related areas have made it possible to provide sophisticated communication capabilities to the individual soldiers in combat in the battlefields and elsewhere. Heretofore, however, omnidirectional microstrip antenna systems have not been devised for incorporation and mounting on a helmet such as a soldier's helmet, nor for application to any spherical or near spherical surface. Helmet antennas which do not involve microstrip patch antenna elements are described in U.S. Pat. Nos. 3,582,951; 3,977,003; and 5,438,702.
Also, in U.S. Pat. No. 4,527,163 there is described an omnidirectional microstrip antenna system on a vertical cylindrical surface which is designed to broadcast 360.degree. in azimuth and a certain angular sector in elevation for satisfying a specific system performance requirement. In U.S. Pat. No. 4,922,259 there is described a microstrip antenna system placed inside the nose cone of an airplane that is required when in flight to maintain constant communication with a ground station. However, other than the fact that these two patents deal with microstrip antennas for providing omnidirectional or wide-angle coverages, they are not directly related to the integration of a microstrip antenna system in a soldier's helmet as does the present invention.